Catalytic combustion of acetonitrile over CuCeOx-HZSM-5 composite catalysts with different mass ratios: The synergism between oxidation and hydrolysis reactions

A sequence of CuCeO x -HZSM-5 composite catalysts at different Cu-Ce loading synthesized by the citric acid complex impregnation method were evaluated for the catalytic oxidation of acetonitrile. Among which, the 2CuCeO x -HZSM-5 sample exhibited the best degradation efficiency. In the temperature range of 225–350 °C, its activity and mineralization rate were approximately 100%, and the N 2 selectivity remained more than 93%. The characterization results revealed that all the samples showed an existence of isolated Cu 2+ species. And more Cu-Ce mixed oxides covered on HZSM-5 at an elevated Cu-Ce content, leading to the enhanced reducibility. In situ DRIFTS results showed that both oxidation and hydrolysis reaction routes proceeded during the degradation of acetonitrile over the composite catalysts. Their synergism was crucial to guarantee both high activity and N 2 selectivity. The highly dispersed CuO x species ensured the superior activity of the 2CuCeO x -HZSM-5 sample. And Cu 2+ exchanged HZSM-5 zeolite would be beneficial to N 2 selectivity owing to the improved internal SCR (Selective Catalytic Reduction) reaction to reduce NO x from oxidation routes. Additionally, the mineralization rate was lowered with the formation of carbonaceous products like CH 4 and CO for the catalysts at low Cu-Ce loading due to the lack of redox capacity.